man2/setxattr.2

   1 .\"
   2 .\" Extended attributes system calls manual pages
   3 .\"
   4 .\" (C) Andreas Gruenbacher, February 2001
   5 .\" (C) Silicon Graphics Inc, September 2001
   6 .\"
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  27 .TH SETXATTR 2 2001-12-31 "Linux" "Linux Programmer's Manual"
  28 .SH NAME
  29 setxattr, lsetxattr, fsetxattr \- set an extended attribute value
  30 .SH SYNOPSIS
  31 .fam C
  32 .nf
  33 .B #include <sys/types.h>
  34 .B #include <attr/xattr.h>
  35 .sp
  36 .BI "int setxattr(const char\ *" path ", const char\ *" name ,
  37 .BI "              const void\ *" value ", size_t " size ", int " flags );
  38 .BI "int lsetxattr(const char\ *" path ", const char\ *" name ,
  39 .BI "              const void\ *" value ", size_t " size ", int " flags );
  40 .BI "int fsetxattr(int " fd ", const char\ *" name ,
  41 .BI "              const void\ *" value ", size_t " size ", int " flags );
  42 .fi
  43 .fam T
  44 .SH DESCRIPTION
  45 Extended attributes are
  46 .IR name :\c
  47 .I value
  48 pairs associated with inodes (files, directories, symbolic links, etc.).
  49 They are extensions to the normal attributes which are associated
  50 with all inodes in the system (i.e., the
  51 .BR stat (2)
  52 data).
  53 A complete overview of extended attributes concepts can be found in
  54 .BR attr (5).
  55 .PP
  56 .BR setxattr ()
  57 sets the
  58 .I value
  59 of the extended attribute identified by
  60 .I name
  61 and associated with the given
  62 .I path
  63 in the filesystem.
  64 The
  65 .I size
  66 of the
  67 .I value
  68 must be specified.
  69 .PP
  70 .BR lsetxattr ()
  71 is identical to
  72 .BR setxattr (),
  73 except in the case of a symbolic link, where the extended attribute is
  74 set on the link itself, not the file that it refers to.
  75 .PP
  76 .BR fsetxattr ()
  77 is identical to
  78 .BR setxattr (),
  79 only the extended attribute is set on the open file referred to by
  80 .I fd
  81 (as returned by
  82 .BR open (2))
  83 in place of
  84 .IR path .
  85 .PP
  86 An extended attribute name is a simple null-terminated string.
  87 The
  88 .I name
  89 includes a namespace prefix; there may be several, disjoint
  90 namespaces associated with an individual inode.
  91 The
  92 .I value
  93 of an extended attribute is a chunk of arbitrary textual or
  94 binary data of specified length.
  95 .PP
  96 The
  97 .I flags
  98 parameter can be used to refine the semantics of the operation.
  99 .B XATTR_CREATE
 100 specifies a pure create, which fails if the named
 101 attribute exists already.
 102 .B XATTR_REPLACE
 103 specifies a pure replace operation, which fails if the
 104 named attribute does not already exist.
 105 By default (no flags), the extended attribute will be created if
 106 need be, or will simply replace the value if the attribute exists.
 107 .SH RETURN VALUE
 108 On success, zero is returned.
 109 On failure, \-1 is returned and
 110 .I errno
 111 is set appropriately.
 112 .PP
 113 If
 114 .B XATTR_CREATE
 115 is specified, and the attribute exists already,
 116 .I errno
 117 is set to
 118 .BR EEXIST .
 119 If
 120 .B XATTR_REPLACE
 121 is specified, and the attribute does not exist,
 122 .I errno
 123 is set to
 124 .BR ENOATTR .
 125 .PP
 126 If there is insufficient space remaining to store the extended attribute,
 127 .I errno
 128 is set to either
 129 .BR ENOSPC ,
 130 or
 131 .B EDQUOT
 132 if quota enforcement was the cause.
 133 .PP
 134 If extended attributes are not supported by the filesystem, or are disabled,
 135 .I errno
 136 is set to
 137 .BR ENOTSUP .
 138 .PP
 139 The errors documented for the
 140 .BR stat (2)
 141 system call are also applicable here.
 142 .SH VERSIONS
 143 These system calls have been available on Linux since kernel 2.4;
 144 glibc support is provided since version 2.3.
 145 .SH "CONFORMING TO"
 146 These system calls are Linux-specific.
 147 .\" .SH AUTHORS
 148 .\" Andreas Gruenbacher,
 149 .\" .RI < a.gruenbacher@computer.org >
 150 .\" and the SGI XFS development team,
 151 .\" .RI < linux-xfs@oss.sgi.com >.
 152 .\" Please send any bug reports or comments to these addresses.
 153 .SH SEE ALSO
 154 .BR getfattr (1),
 155 .BR setfattr (1),
 156 .BR getxattr (2),
 157 .BR listxattr (2),
 158 .BR open (2),
 159 .BR removexattr (2),
 160 .BR stat (2),
 161 .BR attr (5)